Aluminium gallium indium phosphide

Molecular structure of AlGaInP

Aluminium gallium indium phosphide (AlGaInP, also AlInGaP, InGaAlP, etc.) is a semiconductor material that provides a platform for the development of novel multi-junction photovoltaics and optoelectronic devices, as it spans a direct bandgap from deep ultraviolet to infrared.^[1]

AlGaInP is used in manufacture of light-emitting diodes of high-brightness red, orange, green, and yellow color, to form the heterostructure emitting light. It is also used to make diode lasers.

Formation

AlGaInP layer is often grown by heteroepitaxy on gallium arsenide or gallium phosphide in order to form a quantum well structure.

Heteroepitaxy is a kind of epitaxy performed with materials that are different from each other. In heteroepitaxy, a crystalline film grows on a crystalline substrate or film of a different material.

This technology is often used to grow crystalline films of materials for which single crystals cannot 1D View

Another example of heteroepitaxy is gallium nitride (GaN) on sapphire^[2]

Properties

AlGaInP is a semiconductor, which means that its valence band is completely full. The eV of the band gap between the valence band and the conduction band is small enough that it is able to emit visible light (1.7eV - 3.1eV). The band gap of AlGaInP is between 1.81eV and 2eV. This corresponds to Red, orange, or yellow light, and that is why the LED's made from AlGaInP are those colors.^[1]

-Other chemical properties can be seen below.

Chemical properties of AlGaInP

-The optical properties of AlGaInP are shown below

Optical Properties of AlGaInP

Zinc Blende Structure

AlGaInP's structure is categorized within a specific unit cell called the Zinc Blende Structure ^[3](which can be seen pictured below). Zinc blende/sphalerite is based on a FCC lattice of anions. It has 4 asymmetric units in its unit cell. It is best thought of as a face-centered cubic array of anions and cations occupying one half of the tetrahedral holes. Each ion is 4-coordinate and has local tetrahedral geometry. Zinc blende is its own antitype—you can switch the anion and cation positions in the cell and it doesn't matter (as in NaCl). In fact, replacement of both the Zn and S with C gives the diamond structure!^[4]

Also shown below are the characteristics of the zinc blende structure.^[4]

Statistics of the Zinc Blende structure

A zincblende unit cell

Applications

AlGaInP can be applied to many things. Some of the things here will be described further down.

•Light emitting diodes of high brightness

•Diode lasers (could reduce laser operating voltage)

•Quantum well structure.

•Campesato R et al studied the properties of aluminium gallium indium phosphide for application in the next-generation of high-efficiency multi-junction solar cells. The high direct band gap of this semiconductor makes it one of the most promising candidates for the manufacture of the top junction layers in multi-junction solar cells.

•Solar cells (potential). The use of aluminium gallium indium phosphide with high aluminium content, in a five junction structure, can lead to solar cells with maximum theoretical efficiencies (Solar cell efficiency) above 40%^[1]

AlGaInP Laser

The aluminium gallium indium phosphide laser is a type of visible-light diode laser. Visible diode lasers emit wavelengths of red and green in the visible spectrum of electromagnetic radiation. The diode lasers consist of a semiconductor material in which the p-n junction forms the active medium. The AlGaInP laser emits wavelengths of 0.63-0.9 µm. Each of these wavelengths is used for different applications. Some of the other applications of the AlGaInP laser are listed below:^[5]

•The primary application AlGaInP laser is in optical disc readers, DVD players and compact disc players^[1]

(Recently, an AlGaInP type semiconductor laser device has been put into practical use as a light source for recording and reading out data (information) in an optical information processing system such as a magneto-optical disk or an optical disk.)^[6]

•Laser pointers

•Gas sensors

•Pumping sources

•Machining^[1]

LED

AlGaInP can be used as an LED. An LED is composed of a p-n junction which contain a p-type and an n-type. In this p-n junction, the p-type is AlGaIn, and the n-type is P. The material used in the semiconducting element of an LED determines its color.^[7]

AlGaInP is one of the two main types of LEDs presently used for lighting systems. The other is indium gallium nitride (InGaN)

Slight changes in the composition of these alloys changes the color of the emitted light.

AlGaInP alloys for red, orange and yellow LEDs

InGaN alloys for green, blue and white LEDs

Safety and toxicity aspects

The toxicology of AlGaInP has not been fully investigated. The dust is an irritant to skin, eyes and lungs. The environment, health and safety aspects of aluminium indium gallium phosphide sources (such as trimethylgallium, trimethylindium and phosphine) and industrial hygiene monitoring studies of standard MOVPE sources have been reported recently in a review.^[8] The AlGaInP laser is has also been shown in a study to slow the healing of skin wounds in laboratory rats.^[9]

See also

• Indium phosphide
• Gallium indium phosphide
• Aluminium gallium phosphide
• Indium gallium arsenide phosphide

References

Notes